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Square intake port vs. round intake port: when did it change?


720inOlyWa

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I have both Z24 head versions and both are fresh and ready to go into my most recent acquisition, should one be required. But this new truck is an 84, and I won‘t know which version it is until I remove the intake manifold, I reckon. Does anyone know when they switched over from round to squarish?

 

Most that I see are the squarish intake port heads. In fact, I mistakenly used a round intake port on a squarish intake port head and it seemed to run fine for 15k miles. So I also wonder if it makes a difference at all if you interchange them. 

 

anyone know?

 

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Changed when the Z24 came out October '82 or a few months into the '84 model year to replace the Z22. It's strictly found only on the Z24 although the head and the intake will work just as well on a Z20 or Z22. You can interchange the round and square port intakes but....

 

z24topz20bottom.jpg

 

Top is one of my Z24 heads. Below is a Z20/Z22 head.

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Changed when the Z24 came out October '82 or a few months into the '84 model year to replace the Z22. It's strictly found only on the Z24 although the head and the intake will work just as well on a Z20 or Z22. You can interchange the round and square port intakes but....

 

z24topz20bottom.jpg

 

Top is one of my Z24 heads. Below is a Z20/Z22 head.

 

 

But what? It aint right?

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Z24 heads only have square intakes. A Z24 head can be identified by the fuel pump opening not being machined out. Just like the top head in my picture.

 

It's possible that someone may have swapped a Z22 head on but if a Z24 head it will have square intake ports and should have a square intake to match.

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Got it. Thanks!

This clarifies the picture on the service history of the poor old Fudgecicle.  The Z22 head, was only one of the shakey bits that I have come across. The drivetrain was really cobbled together out of shite. Now it is all replaced / rebuilt.

 

Does anyone have any use for a relatively fresh Z22 head?....

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Well, I am in luck, I guess.  I hooked up the garden hose to the concrete sink in the garage and did some hot water cleaning under the hood of this new acquisition and discovered it has a Z20 engine. That means my fresh-is Z22 head I have laying around will work nicely. The engine itself had a bead of silicone laid in around the rubber gasket on the valve cover, suggesting a futile attempt to stop oil leaks around the cover. The cleanup suggested that oil was seeping from the cover for a while. I take this to suggest that perhaps the valve guides are worn and were pumping oil up top, so swapping out the head and performing a preemptive head gasket replacement should go a ways towards pleasant driving. It will also give me a chance to inspect the cylinders themselves.

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